{"id":"CVE-2026-21265","aliases":["EUVD-2026-2100","GHSA-xqxc-72vf-v8f5","UBUNTU-CVE-2026-21265"],"status":"published","title":"Secure Boot Certificate Expiration Security Feature Bypass Vulnerability","description":"Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.\nThe operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.\n\n\n\nCertificate Authority (CA)\nLocation\nPurpose\nExpiration Date\n\n\n\n\nMicrosoft Corporation KEK CA 2011\nKEK\nSigns updates to the DB and DBX\n06/24/2026\n\n\nMicrosoft Corporation UEFI CA 2011\nDB\nSigns 3rd party boot loaders, Option ROMs, etc.\n06/27/2026\n\n\nMicrosoft Windows Production PCA 2011\nDB\nSigns the Windows Boot Manager\n10/19/2026\n\n\n\nFor more information see this CVE and Windows Secure Boot certificate expiration and CA updates.","severity":{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.01096,"percentile":0.6606,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-1329"],"published":"2026-01-13T17:56:04Z","modified":"2026-07-30T21:17:13Z","affected":[{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"secureboot-db","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1","1.4~ubuntu0.14.04.1"]},{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"shim","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.4-0ubuntu4","0.8-0ubuntu2","0.9+1474479173.6c180c6-1ubuntu1","13-0ubuntu2"]},{"source":"osv","ecosystem":"Ubuntu:14.04:LTS","package":"shim-signed","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3","1.4","1.5","1.6","1.9","1.17~14.04.1","1.18~14.04.1","1.19~14.04.1","1.32~14.04.2","1.33.1~14.04.2","1.33.1~14.04.3","1.33.1~14.04.4","1.33.1~14.04.5"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"secureboot-db","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.1","1.4~ubuntu0.16.04.1"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"shim","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.8-0ubuntu2","0.9+1474479173.6c180c6-1ubuntu1","13-0ubuntu2","15+1533136590.3beb971-0ubuntu1","15+1552672080.a4a1fbe-0ubuntu2","15.4-0ubuntu7"]},{"source":"osv","ecosystem":"Ubuntu:16.04:LTS","package":"shim-signed","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.11","1.12","1.17~16.04.1","1.18~16.04.1","1.19~16.04.1","1.27~16.04.1","1.28~16.04.1","1.32~16.04.1","1.33.1~16.04.1","1.33.1~16.04.2","1.33.1~16.04.3","1.33.1~16.04.4","1.33.1~16.04.5","1.33.1~16.04.6","1.33.1~16.04.10"]}],"products":[{"vendor":"microsoft","product":"windows 10 version 1607"},{"vendor":"microsoft","product":"windows 10 version 1809"},{"vendor":"microsoft","product":"windows 10 version 21h2"},{"vendor":"microsoft","product":"windows 10 version 22h2"},{"vendor":"microsoft","product":"windows 11 version 23h2"},{"vendor":"microsoft","product":"windows 11 version 24h2"},{"vendor":"microsoft","product":"windows 11 version 25h2"},{"vendor":"microsoft","product":"windows server 2012"},{"vendor":"microsoft","product":"windows server 2012 (server core installation)"},{"vendor":"microsoft","product":"windows server 2012 r2"},{"vendor":"microsoft","product":"windows server 2012 r2 (server core installation)"},{"vendor":"microsoft","product":"windows server 2016"},{"vendor":"microsoft","product":"windows server 2016 (server core installation)"},{"vendor":"microsoft","product":"windows server 2019"},{"vendor":"microsoft","product":"windows server 2019 (server core installation)"},{"vendor":"microsoft","product":"windows server 2022"},{"vendor":"microsoft","product":"windows server 2022, 23h2 edition (server core installation)"},{"vendor":"microsoft","product":"windows server 2025"},{"vendor":"microsoft","product":"windows server 2025 (server core installation)"},{"vendor":"microsoft","product":"windows_10_1607"},{"vendor":"microsoft","product":"windows_10_1809"},{"vendor":"microsoft","product":"windows_10_21h2"},{"vendor":"microsoft","product":"windows_10_22h2"},{"vendor":"microsoft","product":"windows_11_23h2"},{"vendor":"microsoft","product":"windows_11_24h2"},{"vendor":"microsoft","product":"windows_11_25h2"},{"vendor":"microsoft","product":"windows_server_2012"},{"vendor":"microsoft","product":"windows_server_2016"},{"vendor":"microsoft","product":"windows_server_2019"},{"vendor":"microsoft","product":"windows_server_2022"},{"vendor":"microsoft","product":"windows_server_2022_23h2"},{"vendor":"microsoft","product":"windows_server_2025"}],"references":[{"url":"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265","tags":["vendor-advisory","patch","Vendor Advisory","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-21265"},{"url":"https://github.com/advisories/GHSA-xqxc-72vf-v8f5"},{"url":"https://ubuntu.com/security/CVE-2026-21265","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-21265","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-21265","title":"Secure Boot Certificate Expiration Security Feature Bypass Vulnerability","description":"Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.\nThe operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.\n\n\n\nCertificate Authority (CA)\nLocation\nPurpose\nExpiration Date\n\n\n\n\nMicrosoft Corporation KEK CA 2011\nKEK\nSigns updates to the DB and DBX\n06/24/2026\n\n\nMicrosoft Corporation UEFI CA 2011\nDB\nSigns 3rd party boot loaders, Option ROMs, etc.\n06/27/2026\n\n\nMicrosoft Windows Production PCA 2011\nDB\nSigns the Windows Boot Manager\n10/19/2026\n\n\n\nFor more information see this CVE and Windows Secure Boot certificate expiration and CA updates.","status":"published","published":"2026-01-13T17:56:04.224Z","modified":"2026-07-30T20:46:20.081Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"medium","assessor":"cna"}],"cwes":["CWE-1329"],"updated_at":"2026-11-02T13:41:42.05254Z"}],"euvd":[{"id":"EUVD-2026-2100","description":"Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.\nThe operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.\n\n\n\nCertificate Authority (CA)\nLocation\nPurpose\nExpiration Date\n\n\n\n\nMicrosoft Corporation KEK CA 2011\nKEK\nSigns updates to the DB and DBX\n06/24/2026\n\n\nMicrosoft Corporation UEFI CA 2011\nDB\nSigns 3rd party boot loaders, Option ROMs, etc.\n06/27/2026\n\n\nMicrosoft Windows Production PCA 2011\nDB\nSigns the Windows Boot Manager\n10/19/2026\n\n\n\nFor more information see this CVE and Windows Secure Boot certificate expiration and CA updates.","status":"published","published":"2026-01-13T17:56:04Z","modified":"2026-07-30T20:46:20Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","level":"medium"}],"updated_at":"2026-11-02T18:02:27.233735Z"}],"ghsa":[{"id":"GHSA-xqxc-72vf-v8f5","title":"Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original...","description":"Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.\nThe operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.\n\n\n\nCertificate Authority (CA)\nLocation\nPurpose\nExpiration Date\n\n\n\n\nMicrosoft Corporation KEK CA 2011\nKEK\nSigns updates to the DB and DBX\n06/24/2026\n\n\nMicrosoft Corporation UEFI CA 2011\nDB\nSigns 3rd party boot loaders, Option ROMs, etc.\n06/27/2026\n\n\nMicrosoft Windows Production PCA 2011\nDB\nSigns the Windows Boot Manager\n10/19/2026\n\n\n\nFor more information see this CVE and Windows Secure Boot certificate expiration and CA updates.","status":"published","published":"2026-01-13T18:31:11Z","modified":"2026-01-13T18:31:19Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H","level":"medium"}],"cwes":["CWE-1329"],"updated_at":"2026-11-02T15:05:35.156514Z"}],"nvd":[{"id":"CVE-2026-21265","description":"Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.\nThe operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.\n\n\n\nCertificate Authority (CA)\nLocation\nPurpose\nExpiration Date\n\n\n\n\nMicrosoft Corporation KEK CA 2011\nKEK\nSigns updates to the DB and DBX\n06/24/2026\n\n\nMicrosoft Corporation UEFI CA 2011\nDB\nSigns 3rd party boot loaders, Option ROMs, etc.\n06/27/2026\n\n\nMicrosoft Windows Production PCA 2011\nDB\nSigns the Windows Boot Manager\n10/19/2026\n\n\n\nFor more information see this CVE and Windows Secure Boot certificate expiration and CA updates.","status":"published","published":"2026-01-13T18:16:25.053Z","modified":"2026-07-30T21:17:13.597Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-1329"],"updated_at":"2026-11-02T14:12:04.066712Z"}],"osv":[{"id":"UBUNTU-CVE-2026-21265","description":"Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot. The operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees. Certificate Authority (CA) Location Purpose Expiration Date Microsoft Corporation KEK CA 2011 KEK Signs updates to the DB and DBX 06/24/2026 Microsoft Corporation UEFI CA 2011 DB Signs 3rd party boot loaders, Option ROMs, etc. 06/27/2026 Microsoft Windows Production PCA 2011 DB Signs the Windows Boot Manager 10/19/2026 For more information see this CVE and Windows Secure Boot certificate expiration and CA updates.","status":"published","published":"2026-01-13T18:16:00Z","modified":"2026-01-21T18:26:31.100707Z","cvss":[{"version":"3.1","score":6.4,"vector":"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H","level":"medium"}],"updated_at":"2026-11-02T16:56:01.334185Z"}]}}